In recent years, there has been a lot of empirical evidence that relate diet to brain health. For instance, research has found a relationship between a healthy diet, protection from depression and maintenance of cognitive functioning and brain volume into old age. But these studies have all been correlational, meaning that they establish an association between diet and brain health, not that one causes the other.
A healthy diet can improve depression symptoms significantly and even lead to remission of depression. The likelihood that a person with clinical depression will experience remission solely from a high quality diet is one in four.
In this landmark study, Felice Jacka from Deakin University in Australia and her colleagues were the first to use a randomized controlled design to test whether diet quality can actually treat clinical depression. The participants, recruited from the community, had an average age of 40 and moderate to severe depression. In addition, the quality of their diets was poor: low intake of fibre, lean proteins and fruit and vegetables, and a high intake of sweets, processed meats and salty snacks.
The participants were divided into two groups: the dietary support group (DS group) and the social support group (SS group). The DS group received personalized dietary advice and support to help them adhere to the recommended diet. They were encouraged to eat vegetables, fruits, whole grains, legumes, fish, lean red meats, olive oil, and nuts and avoid eating sweets, refined cereals, fried food, fast-food, processed meats, and sugary drinks. The SS group followed the same visit schedule and length during which they talked about topics of interest with a facilitator or played cards or board games.
At the end of the 3-month study, one-third of those on the healthy diet were in remission from depression compared to only 8% for the social support group.
After 12 weeks of support, those in the DS group showed significantly greater improvement in depression symptoms than those in the SS group. In addition, one-third of those in the DS group were in remission from depression compared to only 8% for the SS group. And those who adhered more closely to the dietary recommendations showed the greatest improvement. This study also found that the number needed to treat (NNT) was 4.1, meaning that the likelihood that a person with clinical depression will experience remission solely from a high quality diet is one in four. These are astounding statistics, and don’t even take into account the improvement of depression symptoms!
We must ask our clients about the quality of their diets and encourage them to eat healthy food. Not to do so does them a disservice and can hinder the process of change.
As coaches, we often see clients with sub-clinical depression. Although this study did not look at sub-clinical depression, we can’t say for sure that the the results generalize to low mood. Nevertheless, together with the correlational research, it definitely points to that direction. I think it’s imperative that we ask our clients about the quality of their diets and encourage them to eat healthy food. Not to do so is doing them a disservice and can hinders the process of change. That’s because we can’t have a healthy mind without a healthy body.